Astroprof’s Page

How does the Flag Wave on the Moon?

Published on Aug 13, 2006 at 1:00 am. 34 Comments.
Filed under moon, space exploration.

People often ask me, “How can the flag on the Moon wave if there is no air?” Well, that would be a good question, if the flag actually waved on the Moon. People see the image shown here, and it looks like the astronaut is standing beside a flag that is standing out straight in a stiff breeze. That is what it is supposed to look like! However, there is no wind at all. So, how does the flag stay extended like that?

Well, quite simply, NASA wanted to have a flag to plant in the lunar surface. There is no wind, so the flag would just hang there limp. That would not be very impressive. Also, it would be just a swatch of colored fabric in photos. There would be no way to tell that it was an American flag. So, they came up with an ingenious way of sticking a flag in the surface that looked like it were waving. The fabric of the flag has a wire mesh sewn into it. The flag rolls up into a nice little package. When on the Moon, the astronauts extend the pole and stick it into the ground. They can then unroll the flag. Working in heavy spacesuits, though, it is easier to unroll the flag and then stick it into the ground. The lunar surface is grainular and tough to poke the flag into. So, they have to rock the pole back and forth shoving it down into the ground. Watching on the TV, this back and forth motion makes the flag swing back and forth like it is waving.

The wire mesh is sewn into the fabric so that the flag will appear to stand out straight in the absense of wind. But, a flag sticking straight out from the pole doesn’t look natural. So, the astronauts often would extend the flag and bend ripples into it so that it looked more like it were waving. Look at video of the astronauts moving around the flag. It looks like it is waving, but it is frozen in position as the astronauts move by. It doesn’t actually wave. As it turns out, the flag didn’t really unroll as smoothly on the Moon as it did in tests on Earth, so the astronauts didn’t have to do much work to make it look like it were waving. It tended to look crinkly anyway.

My final image is of the flag left by Apollo 11, as seen from the lunar lander. Without weather, one would expect that this scene would remain like this forever. But, that isn’t quite what happened. When the ascent module took off, the blast from the exhaust of the rocket engine blew over the flag. Just before it blew over, the blast shook it. This is the only time that the flag actually waved while on the Moon — while it was being blasted with rocket exhaust. Also, sadly, I would imagine that it probably isn’t red, white, and blue anymore. Likely the intense ultraviolet light from the Sun has faded the colors, just as it does to flags on Earth. But, without the protection of the Earth’s atmosphere, the ultraviolet light on the Moon is far stronger than it is on Earth, so I would be rather surprised if after this much time any color is left.

-Astroprof

Images courtesy of NASA

34 Comments to ‘How does the Flag Wave on the Moon?’:

Andrew on August 13, 2006 at 2:05 pm: 1

What type of material was the flag made with?.I also wonder if with so much UV light,if it has become essentially dust at this point.Leaving of course, the mesh woven into the fabric behind?.
Astroprof on August 13, 2006 at 3:39 pm: 2

You might be right. I don’t know if it is true of all six flags, but the Apollo 11 flag started off as a simple requisition of a standard government issue nylon flag. Nylon will break down in UV. So, perhaps there isn’t much left now.
allison on March 15, 2007 at 12:46 pm: 3

oh my gosh,that is like so cool!!!!!!My dad & i were just sitting in our living room going over my science study guide,when we came to the question “which of these is true?”& i said B.,THERE IS NO WIND OR WATER ON THE MOON.Then my dad asked me to ask my teacher the next day “if there is no wind or water on the moon, then why was the flag blowing in the wind when Astroprof stuck it in the moon?”So the next day i asked my teacher & she said “i don’t know allison,that’s a very good question!Then my other teacher,ms.ross,said “maybe you should write to the nasa one day.And that’s my story!!!!
Ryan on April 2, 2007 at 1:08 pm: 4

…There are videos of the flag waving, and not during liftoff from the surface - NOt just pictures showing it meshed-up. The flag clearly moves and shifts and waves in some wind - check it out yourself. I came here looking for the answer to my question and only found partial adresses to a real problem.
Astroprof on April 2, 2007 at 1:25 pm: 5

There are no videos of the flag waving in wind. The only times that it waves is when it is being buffeted by the exhaust of the ascending rocket, it is being pushed into the ground, the pole or the ground near the pole is being disturbed by an astronaut, or it the oscillations of such are damping right after such an event. Anyone who tells you otherwise is trying to pull the wool over your eyes.
Sean on April 26, 2007 at 9:02 pm: 6

Interesting! Several months ago a guy behind the counter at our local gas station asked me if I could explain how the flag on the moon moves considering the atmosphere of the moon is essentially a vacuum. Assuming he might be correct about the flag moving, and after thinking about it, my hypothetical explanation was as follows: Although there are no molecules to create wind, perhaps the different colors of the flag absorb and reflect energy from the sun at different rates and magnitudes, and much like one of those gadgets with white and dark diamonds in a light bulb-like vacuum chamber spinning when a light is turned on, so moves the flag. However, the wire mesh and movement from rocket exhaust” explanation(s) make more sense. My question now has to do with gravity vs. the wire mesh. Even though the gravitational force of the moon is only ~15% of that of the earth, in the absence of a both a wire mesh and a “photon wind”, wouldn’t an initially extended flag eventually fall into a drooping position?
Astroprof on April 26, 2007 at 10:03 pm: 7

Certainly. If there were no wire mesh, then the flag would just hang limply, and NASA didn’t think that would look good, so that is why they added the wire mesh.
Kristoff on July 27, 2007 at 2:54 pm: 8

I love how people still don’t believe we were on the moon… I would imagine these are the same people who think that GWB was the one who created 911…

listen to this man people, he has explained it more than anyone really deserves… and I thank him for doing so…
Amy on November 13, 2007 at 11:37 pm: 9

That was awesome…..I needed to do a report on how the flag can stay up on the Moon.Guess I found the answers!
unipal390 on February 7, 2008 at 2:18 pm: 10

I believe all the apollo moon landings were a hoax theres too much evidence to prove it, a) the flag swaying, b)astro belt, c) no blast crater yet on the posters released by nasa clearly picture a blast crater. d) where are the stars?? lol e) compare backgrounds that supposedly are 2miles apart, same background.
Astroprof on February 7, 2008 at 2:22 pm: 11

Actually, there is overwhelming evidence that the landings were real. There are the reflectors left on the Moon, the moon rocks, etc.

The flag doesn’t sway. What astro belt? There is a small scooped away area under each lander in photos, and the stars are FAR too dim to show up in short exposure photographs. And, looking at distant objects from only two miles different positions looks similar even here on Earth.
Rick C. on February 16, 2008 at 5:10 pm: 12

While watching the DVD In the Shadow of the Moon I noticed that the flag moved slightly right after the astronaut jammed the flag pole into the ground. As he hopped away the pole moved slightly and the flag appeared to ripple. I assume gravity played a small part and the energy of the pole moving was transfered to the flag’s material giving it the illusion of blowing in the wind. The scene was captured from other angles too. The best angle is the one that viewers have seen most often on the Internet (youtube). I’ve compared both videos at the same time. Each angle the flag is moving while being touched. But the youtube video gives the impression that it is moving untouched while an astronaut hops past even though it is directly after being touched. This, I believe, is the root of the wind blown flag mythology.
kyren on May 3, 2008 at 7:00 pm: 13

Thanks man I needed this for my thesis paper. Also, to all the nut jobs out there who believe that the moon landings were fake, just shut up, we’re tired of your idiotic ideals and obnoxious opinions.
vishal on May 9, 2008 at 4:11 am: 14

Is this true, the saying that man not landed on moon. I just see pictures of flag waving on moon. But how??????????
lol) its is so wrong. What do u thimk astroprof?
Astroprof on May 9, 2008 at 9:01 am: 15

As I said, the flag doesn’t wave. And, we know for a fact that men went to the Moon. After all they brought back rocks and they left reflectors there that we bounce lasers from.
lizeth on May 25, 2008 at 8:05 pm: 16

this is exactly what i was looking for .?
Poop'n Head Wilson on June 9, 2008 at 1:34 am: 17

if you watch the new t.v. program called “when we left earth:The Nasa missions” (on Discovery channel) they show video of the flag “Moving in a waving motion” with no one making any contact with it, with the flag already unrolled&the craft still on the moon/not blasting off.. at least I think thats what I saw, I don’t remember now lmao. also, you cant see stars twinkle in the background ,because there is no atmosphere on the moon like earth. dont get me wrung, I agree with the fact we landed on the moon . please send me a friend request - http://www.myspace.com/nicky1069
Astroprof on June 9, 2008 at 11:52 am: 18

If you look carefully at the video, which was in their introductory sequence, you’ll notice that it was when the ascent stage was taking off from the Moon. Yes the flag was moving around, and even fell over, as a result of the rocket exhaust. But, it did not “wave” on its own. Also, if you are looking out the window of the craft, then you cannot trust the star images that you see. Everything is distorted through those windows. Cameras that were out in the vacuum did not see stars twinkling.

Sorry, I don’t do the whole myspace thing.
Prof. Rickover on June 25, 2008 at 12:54 pm: 19

The moon ‘hoax’ idiots are paranoid that humans did something epic without involving them in it - at least that’s my view. As for propagation from one generation to the next, it can only be the same type of low-intelligence fools that are in need of something to belong to i.e. moon hoax theory believers. The opposite side of that coin is the well-meaning idiots that acknowledge the moon landings as fact - but with incredibly faulty data to back them up i.e. ‘We did so land on the moon! I’ve seen the space shuttle lift off and take people to Mars’

As academics, we’re forced to acknowledge that idiocy is a cottage industry that will never go away. I need only nod at the Flat Earth Society as a case in point. NOTE: The Flat Earth Society’s explanations of the moon landings are quite entertaining.
FoamyJr on June 25, 2008 at 6:28 pm: 20

I have recently reviewed the videos of an Apollo 15 astronaut passing in front of the flag on YouTube and have seen the flag subsequently moving.

I have always wondered if this might be caused by the kicking up of dirt caused by the way the astronauts hopped.

Whenever you see video of how the astronauts skipped to move, there is always a frontward spray of dust, and the spray is more accentuated the faster they moved. You can see the astronaut in question is moving at a fair speed. In such low gravity (not too mention, a vacuum), the mass of even a little dust hitting the flag would cause it to react with slight movement.

This seems to me to be a far more reasonable explanation then anything else I’ve seen. Any thoughts, Astroprof?
Mr. Physics on June 25, 2008 at 9:15 pm: 21

Don’t forget people - Things can move even without air. How else do you explain planets, stars, asteroids, comets, etc.
Be sure that you distinguish the CAUSE of the motion you are discussion. Is the motion due to the astronauts moving the flag pole around? If so, the inertia of the flag’s material can cause it to continue moving after the astronauts stopped moving the pole! This gives the flag the illusion of “rippling” in the wind.

Study your physics in order to answer questions about the universe!
Prof. Rickover on June 25, 2008 at 11:49 pm: 22

“Don’t forget people - Things can move even without air. How else do you explain planets, stars, asteroids, comets, etc.”

Say what? I’m so confused.
Mr. Physics on July 26, 2008 at 6:30 pm: 23

Mr. Physics.
You don’t talk physics.
You talk nonsense.
You make no sense.

Please, don’t call yourself Mr. Physics. It doesn’t suit you at all.

Thank you
Kind regards,
Mr. Physics (I just gave your name a proper home)
Astroprof on July 30, 2008 at 1:39 pm: 24

OK, people, play nice.

I have had to remove several comments where foul language was used. Let us act like adults here.

I find it amazing that so many people have trouble believing that we went to the Moon when all the evidence points to that. It never amazes me how some people would rather believe in some sort of conspiracy than to admit that someone could do something pretty big.
Planet Football on August 4, 2008 at 5:50 pm: 25

Astroprof, I can understand the questioning of the moon landings. However, if it was hoaxed in a hollywood studio im sure they would of uncovered it by now with the amount of people who would of been involved in the cover up. I mean, im sure Speilburg can tell a staged set if he saw one! Also, we must remember that the U.S looked at the space race with the Russians as a morale boost for the country during the Cold War, bragging rights and missile technology advances. So if they would take a risk in lying to a nation, the consequence in them being found out would have been more damaging than good, especially for Mr Kennedy.
Physics Teacher on August 10, 2008 at 10:26 am: 26

ooh took orf me fackin words then eh ??
Cold War this, Cold War that, Cold fackin War shake it all about, I’ll give you a Cold War, a Cold War up the wife’s shitta is what I’ll do
Dayvid on August 29, 2008 at 12:53 am: 27

Mythbusters on the Discovery channel addressed certain conspiracy theories and one of the ones they answered was flag waving on the moon. Had something to do with no air resistance on the moon. They probably have the episode on their website. One of many awesome episodes. Go Mythbusters!
alex on September 2, 2008 at 2:12 pm: 28

I would wonder why dont they go to the moon again like an aniversary thing -foor us morale? I mean it should be a piece of cake now adays in this age and the imaging should be amazing with the technology.This would be a fun thing for america now.I mean the space shuttle can be there to document it all and it would be interesting.
Astroprof on September 2, 2008 at 3:13 pm: 29

Actually, getting to the Moon is difficult. All of the people who did it before have retired, or died. We can’t even get the companies that worked as contractors and subcontractors to build the same parts, since many of those companies don’t even exist anymore. And, now we have new technology. So, we have to start all over again from scratch.
Rachel on September 5, 2008 at 10:35 am: 30

Well hi My Name is Rachel Im going my Science HMWK and it is to, so im going to show my teacher up by showing him this site but do you actully have an answer to my question.
Rachel on September 5, 2008 at 10:40 am: 31

OK last message was a mess this is what its surpossed to say

Im doing my Science HMWK and it is to find out ‘Why doesnt a flay wave on the moon, so im going to show my teacher up by showing him this site but do you actully have an answer to my question.
Tom Green on September 11, 2008 at 9:01 pm: 32

hey every one. I completely agree with the fact that we landed on the moon.

does any one have any links to websites that talk about life on the moon? im doing a show about “life that could be” on the moon. please message me back.
College(SpaceCurious) on September 14, 2008 at 8:32 am: 33

Life couldn’t exist in the moon except if there’s a living thing that could withstand 100* C as an average temp in the morning and -13* at night. And it doesn’t even have an atmosphere.

Astroprof….
is there an exact copy of the cam. used on the moon?
if there are any, is it in the market?
Calgary on October 1, 2008 at 3:08 pm: 34

Chinese ‘taikonauts’ Flag Waving in Space Outside the Orbit Module (02:00-03:00)

http://www.youtube.com/watch?v=gMxQEHfU6hM&NR=1